A gasifier generally includes a primary combustion chamber into which solid fuel is loaded on to a grate structure on which it is first dried and gasified via controlled primary combustion. The resultant gas is then transferred into a secondary combustion chamber, which may conveniently be a cycloburner, for further combustion to produce a high temperature relatively clean flue gas able to be used for a variety of purposes, eg. power generation or heating. There is a small residue of inorganic matter.
A gasifier of the general type to which the present invention relates is disclosed, for example in U.S. Pat. No. 4,716,842, and the technology generally is of particular interest in waste recycling, especially with an emphasis on so called “green power” generation. Specific solid fuels which may conveniently be gasified in this way include biological waste, agricultural byproducts, wood waste and biomass.
As with any burner or furnace construction operating at high temperatures, the housing is typically provided with an appropriate renewable lining of refractory material, typically ceramic castings capable of withstanding very high combustion temperatures over extended periods. It has been appreciated in accordance with a first aspect of the present invention that it is possible to improve refractory wall structures for burners and furnaces, whether of the presently discussed type or more generally, in an advantageous manner, by providing what may be viewed as an inverted skeletal configuration.
In a separate aspect, the invention is concerned with enhancing control of the passage by which combustion gases are directed from the primary combustion chamber to the secondary chamber.